SigFig finds that investors who trade frequently — defined as
"investors who have a turnover amount equal to or greater than
their portfolio value in a year" — actually see lower returns
than their peers who are more hands-off.

Granted, if your existing portfolio isn't properly allocated for
your needs, you might not find the "leaving it alone" strategy as
effective as someone whose investments are appropriately
diversified.

It's worth noting, though, that these numbers lend weight to a
core principle of robo-advice companies (and Buffett followers):
That broad, relatively conservative investments like index funds
and ETFs, if left largely alone, can be lucrative.